Date post: | 19-Dec-2015 |
Category: |
Documents |
View: | 215 times |
Download: | 0 times |
Beta decay experiments
Fabrice PiquemalCENBG, University Bordeaux 1 CNRS/IN2P3
and LSM (CEA – CNRS)
Double beta decay and tritium experiments, current and future
Thanks to: G. Gratta, S. Elliot, A. Giuliani, S. Schoenert, Ch. Weinheimer,T. Kishimito, M. Masaharu
- Absolute neutrino mass and neutrino mass hierarchy (SDB, DBD)
- Nature of neutrino : Dirac ( ) or Majorana ( =) (DBD)
- Right-handed current interaction (DBD)
- CP violation in leptonic sector (DBD)
- Search of Supersymmetry and new particles (DBD)
Beta decays: physics case
SDB: Single beta decayDBD: Double beta decay
F. Piquemal (CENBG) LP07 Daegu August 2007
Neutrino properties
Atmospheric (SK)Accelerators (K2K,Minos)
Reactors (CHOOZ)Accelerators (JPARC)
Solar (SNO, SK)Reactors (KamLAND)
tan223
=1.0 ± 0.3 sin2213
< 0.16 tan212
=0.39 ± 0.05
CP
= CP Dirac phase
U
: CP Majorana phase
m2
atm =
m2
31 = (2.3 0.2 ) 10-3 eV2
m2
sol =
m2
12 = (7.9 0.3) 10-5 eV2
Oscillations
F. Piquemal (CENBG) LP07 Daegu August 2007
Neutrino mass
Beta decay mv = |Uei| mi
<2.3 eV
Double beta decay |<m>| = |Uei mi| < 0.2 - 0.8 eV
Cosmology mi =
m1+m2+m3 <~1 eV
Absolute mass ?
m2
m1
2
m2
2
m3
2
Degeneratem
1≈m2≈m3» |mi-mj|
Normal hierarchym
3>>> m
2~m
1
Inverted hierarchym
2~m
1>>m
3
?
Mass hierarchy ?
F. Piquemal (CENBG) LP07 Daegu August 2007
2
2
21/2
dN/dE ~ [ (E0-Ee)2 – mi2 ]1/2:
Beta decay
(A,Z) (A,Z+1) + e- + e
averaged neutrino
mass
Fraction of decay in [Q – m, Q] ~ (E/Qlowest Q value 3H (Q= 18.6
keV)
3
High counting rate Low background
Energy resolution ~ m
me
2 U ei
2 mi
2me
2 U ei
2 mi
2
F. Piquemal (CENBG) LP07 Daegu August 2007
MAINZ: m2 = -0.6 ± 2.2 ± 2.1 eV2
m< 2.3 eV (95% C.L.)
C. Kraus et al., Eur. Phys. J. C 40 (2005) 447
Beta decay: present status
MAC-E spectrometers
SourceElectron analyzer
Electron counter
3H
integral spectrum: select Ee > Eth
Troisk: m2 = -2.3 ± 2.5 ± 2.0 eV2
m< 2.05 eV (95% C.L.)
But systematics from end-point fluctuations not includedF. Piquemal (CENBG) LP07 Daegu August 2007
Improvement of E: 0.93 eV (4.8 eV for Mainz)Larger acceptance
Statistics 100 days 1000 days
Beta decay: KATRIN experiment
Commissioning and start : 2010
Sensitivity m < 0.2 eV
F. Piquemal (CENBG) LP07 Daegu August 2007
5
Other possible process :
V+A current : <m>, <>, <>
Majoron emission : <gM>
Supersymmetry : ’111,
’113
Neutrinoless double beta decay
Light neutrino exchange
T1/2= F(Q,Z) |M0|2 <m>2-1
Phase space factor Nuclear matrix element
<m>= m1|Ue1|2 + m2|Ue2|2.ei + m3|Ue3|2.ei
|Uei|: mixing matrix elements
et: Majorana phases
(A,Z) (A,Z+2) + 2 e-
Schechter-Valle theorem: Majorana neutrinos
L = 2Lepton number violation
Majorana neutrino (=)
Massive neutrino
F. Piquemal (CENBG) LP07 Daegu August 2007
Electron energy sumQ
Arb
itra
ry s
cale
Observables
Angular distribution
Individual electron energy
Half-life T1/2
Allow to distinguish the mechanism
Background : natural radioactivity, radon,neutrons, muons,
Effective neutrino mass and neutrino oscillations
Inverted hierarchy
Normal hierarchy
Degen
erated
Degenerate: can be tested
Inverted hierarchy: tested by the nextgeneration of experiment
Normal hierarchy: inaccessible
F. Piquemal (CENBG) LP07 Daegu August 2007
<m
> in
eV
A lot of improvements have been done but still a factor 2-3 of discrepancyUncertainties for extraction of <m>
T1/2= F(Q,Z) ||2 <m>2-1 5
Nuclear matrix elements
In the following, « latest NME » will refer to these Nuclear Matrix ElementsF. Piquemal (CENBG) LP07 Daegu August 2007
Shell Model - QRPA Two different QRPA calculations
Experiments Isotopes Techniques Main caracteristics
NEMO3 100Mo,82Se Tracking + calorimeter Bckg rejection, isotope choice
SuperNEMO 82Se, 150Nd Tracking + calorimeter Bckg rejection, isotope choice
Cuoricino 130Te Bolometers Energy resolution, efficiency
CUORE 130Te Bolometers Energy resolution, efficiency
GERDA 76Ge Ge diodes Energy resolution, eficiency
Majorana 76Ge Ge diodes Energy resolution, efficiency
COBRA 130Te, 116Cd ZnCdTe semi-conductors Energy resolution, efficiency
EXO 136Xe TPC ionisation + scintillation Mass, efficiency, final state signature
MOON 100Mo Tracking + calorimeter Compactness, Bckg rejection
CANDLES 48Ca CaF2 scintillating crystals Efficiency, Background
SNO++ 150Nd Nd loaded liquid scintillator Mass, efficiency
XMASS 136Xe Liquid Xe Mass, efficiency
CARVEL 48Ca CaWO4 scintillating crystals Mass, efficiency
Yangyang 124Sn Sn loaded liquid scintillator Mass, efficiency
DCBA 150Nd Gazeous TPC Bckg rejection, efficiency
search is a very dynamic field
Talk focuses on the running experiments and on some 100 kg scale projects starting within 5 years
Present situationHeidelberg-Moscow (2001) ~11 kg of enriched Ge diodes in 76Ge (86%) Pure calorimeter
T1/2 = 2.23 1025 yr +0.44-0.31
<m> = 0.32 ± 0.03 eV
2006 new PSA analysis: 6 effect
Claim for discovery since 2002(2002 : 3.1 and 2004: 4
<m> <0.35-1.05 eV (90% CL)
2004: 4
High energy resolution and efficiency
But poor background rejection (pulse shape analysis)
T 1/2 >1.9 1025 yr (90% CL)
35.5 k.yr
0.06 cts/keV/kg/yr
Eur. Phys. J., A 12 (2001) 147
Very controversial result
Future Ge experiments
GERDA (Germany, Italy, Belgium, Russia)
Majorana (USA, Russia, Japan, Canada)
Selection of very pure material (Majorana)Removal of matter (GERDA) Segmentation of detectors for background rejectionUse of liquid nitrogen or argon for active shieldingImprovement of Pulse Shape Analysis
GERDA PHASE I: 17.9 kg of enriched 76Ge (from HM and IGEX) In 1 year of data (no Background) check of Klapdor’s claim Start 2009 at Gran Sasso, results 2010 PHASE II: 40 kg of enriched 76Ge T1/2 > 2 1026 yr in 3 years of data <m> < 110 meV (no background)
Majorana: 30- 60 kg of enriched 76Ge (3 yr) T1/2 > 1. 1026 yr m < 140 meV Start 2011 Collaboration for 1 ton experiment
Reduction of background bya factor 10 – 100 compareto HM
Bolomètres: CUORICINOCuoricino
Heat sink
ThermometerDouble beta decay
Crystal absorber
Signal:∆T = E/C
High energy resolution 5-7 keV (FWHM)Natural abundance for 130Te: 34%High efficiency: 86%
But no electron identificationBackground from internal and surfacecontamination in emitters
Bolometers of TeO2 (Q= 2.528 MeV)
Running at Gran Sasso since 2003F. Piquemal (CENBG) LP07 Daegu August 2007
60Copile up
130Te0vBB
T1/2 > 3. 1024 yr (90% CL) <m> < 0.2 – 1 eV (90% CL)
Expected final sensitivity ~2009: T1/2 > 6. 1024 yr <m> < 0.1 – 0.7 eV
Energy (keV)
11.83 kg.yr
Cuoricino results
Bckg: 0.18 cts/keV/kg/yr
Gamma regionGamma region, dominated by gamma and beta events,
0DBD
Alpha regionAlpha region, dominated by alpha peaks
(internal or surface contaminations)
750 kg of TeO2 203 kg of 130Te
Array of 988 TeO2 5x5x5 cm3 crystals
Improvement of surface event rejection
CUORE
Data taking foreseen in 2011
Nbckg=0.01 cts.keV-1.kg-1.yr-1
T½ > 2.1 1026 yr
<m> < 0.03 – 0.17 eV
Nbckg=0.001 cts.keV-1.kg-1.yr-1
T½ > 6.6 1026 yr
<m> < 0.015 – 0.1 eV
Goal :Nbckg=0.01 cts.keV-1.kg-1.yr-1
Expected sensitivities (5 years of data)
(Italy, USA,Spain)
(Factor 20 compare to Cuoricino)
Central source foil (~50 m thickness)Tracking detector (6180 drift cells) t = 0,5 cm, z = 1 cm ( vertex )
Calorimeter (1940 plastic scintillators + PMTs)Efficiency 8 % Running at Modane Underground lab since 2003
Vertex
events
E1+E2= 2088 keV t= 0.22 ns(vertex) = 2.1 mm
E1
E2
e-
e-
NEMO 3
Multi-isotopes (7 kg of 100Mo, 1 kg of 82Se,…)Identification of electronsVery good bckg rejection (< 10-3 cts/keV/kg/y)Angular distribution and single electron energy(necessary to distinguish the mechanism in caseof discovery)
But modest energy resolution and efficiency
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
Tracko-calo detector
T1/2() > 5.8 1023 yr (90 % C.L.) <m> < 0.6 – 1.3 eVPhases I + II
Phase I, High radon7.6 kg.yr
Phase I + II13.3 kg.yr
[2.8-3.2] MeV: () = 8 % Expected bkg = 8.1 events
Nobserved = 7 events
Nu
mb
er o
f ev
ents
/ 40
keV
Phase II, Low radon5.7 kg.yr
[2.8-3.2] MeV: () = 8 % Expected bkg = 3.0 events
Nobserved = 4 events
Nu
mb
er o
f ev
ents
/ 40
keV
Nu
mb
er o
f ev
ents
/ 40
keV
results 100Mo
T1/2() > 2. 1024 yr (90 % CL) <m> < 0.3 –0.7 eVExpected in 2009
[2.8-3.2] MeV: () = 8 % Expected bkg = 11.1 events
Nobserved = 11 events
SuperNEMO project
Tracko-calo with 100 kg of 82Se or 150Nd(possibility to produce 150Nd with the French AVLIS facility)
3 years R&D program: improvement of energy resolution Increase of efficiency Background reduction …….
2009: TDR2011: commissioning and data taking of first modules in Canfranc (Spain)2013: Full detector running
Modules based on the NEMO3 principleMeasurements of energy sum, angular distributionand individual electron energy
R&D funded by France, UK and Spain
T½ > 2. 1026 yr <m> < 0.05 – 0.09 eV
(France, UK, Russia, Spain, USA, Japan, Czech Republic,Ukraine, Finland)
100 kg 20 modules
EXO
Prototype EXO-200200 kg of 136Xe, no Ba ion taggingInstallation in progress in WIPP underground lab 2007Could measure of 136Xe
Liquid Xe TPC Energy measurement by ionization + scintillationTagging of Baryum ion (136Xe 136Ba++ + 2 e-)
(USA, Canada, Switzerland, Russia)
Large mass of Xe Identification of final state background rejection
But no e- identificationPoor background rejection without Ba ion tagging
R&D for Ba ion tagging in progress
EXO 200 (2 years) T½ > 6.4 1025 yr (90% CL) <m> < 0.27- 0.38 eV
Experiment IsotopeEnriched
isotope mass (kg)
T1/2 (yr) <m> (eV) Start Status
CUORE 130Te 203 2.1 1026 0.03 - 0.07* 2011 Funded
GERDA phase I
phase II76Ge
17.9
40
3. 1025
2. 1026
0.2 – 0.5*
0.07 – 0.2*
2009
2011
Funded
Funded
Majorana 76Ge 30 - 60 1.1026 0.1 – 0.3* 2011 Funded
EXO-200 136Xe 200 6.4 1025 0.2 - 0.7* 2008 Funded
SuperNEMO82Se
150Nd
100
100
2. 1026
1026
0.05- 0.09*
0.072011 R&D
CANDLES 48Ca 0.5 ~0.5 2008 Funded
MOON II 100Mo 120 0.09 – 0.13 ? R&D
DCBA 150Nd 20 ? R&D
SNO++ 150Nd 500 R&D
COBRA116Cd,
130Te420
R&D
SummarySummary* C
alculation
with
NM
E from
Rod
im et al., S
uh
onen
et al., Cau
rier et al. PM
N07
Inverted hierarchy
Normal hierarchy
Degen
erated
m current and future limits
Expected limits2009 – 2015
CUORE,GERDA,Majorana,
SuperNEMO,EXO
Use of « latest NME » for all experiments
.HM Cuoricino NEMO3 Klapdor
claimLimits in 2009
HM,NEMO3, Cuoricino
Single beta decay
KATRIN m < 2.3 eV m < 0.2 eV results in ~2014
Other possibility : bolometers with 187Re (Q=2.47 keV) but long R&D(at least 10 years to reach 0.2 eV)
Double beta decay
Very active field. A claim to be checked
Current experiments will reach a sensitivity on <m> ~(0.2 – 0.7) eV in 2009
Need to measure several nucleus with different techniques (only tracko-calocan distinguish the mechanism in case of discovery)
Next generation ~ source mass 100 – 200 kg. <m> ~ (0.03 – 0.1) eVWill cover partially the inverted hierarchy mass scenario (2011 – 2015)Essential step for 1 ton scale experiment ( background considerations)
Need improvements for Nuclear Matrix Element calculations
SummarySummary
BACKUP SLIDES
2001
T1/2
= (0.8-18.3) 1025 yr <m>= 0.11 – 0.56 eV
2002 (3.1)
2004: new calibration (4)
T 12
0.69 4 . 1 8 10 2 5 ans 90 C L
m 0.28 0 . 5 8 eV Best value:0.39 eV
T1/2
>1.9 1025 <m> < 0.35-1.05 (90%)
signal ? HM claim
signal ?
Estimation of the background level
Problems for some well-known peaks (214Bi)
Some unknow lines in the same region
56Co produced by cosmic rays (2034 keV photon+ 6 keV X-ray) 76Ge(n,)77Ge (2038 keV photon) Some unknown line
Inelastic neutron scattering (n,n‘) on lead
Other suggestions, can be combination of all
(Result with last NME should be <m> = 0.11 – 0.71 eV)
T1/2 = 2.23 1025 yr +0.44-0.31
<m> = 0.32 ± 0.03 eVToday 6
T
/1 > . . A
M . t
NBckg . Eln2 . N
kC.L.
(y)
Experimental techniques
Today, no technique able to optimize all the parameters
M: masse (g) : efficiencyKC.L.: Confidence levelN: Avogadro numbert: time (y)NBckg: Background events (keV-1.g-1.y-1)E: energy resolution (keV)
CalorimeterSemi-conductors
Source = detector
, E
CalorimeterLoaded ScintillatorSource = detector
,
Tracko-caloSource detector
NBckg, isotope choice
Xe TPCSource = detector
,M, (NBckg)
GERDA and MajoranaStrategy: Ge detectors in liquid nitrogen to remove materials Active shielding and segmentation of detectors to reject gamma-rays
e-
detector segments
e-
Liquid argon
scintillation
crystal anti-coincidence Detector segmentation
pulse shape analysis R&D: liquid argon anti-coincidence
From Fedor Simkovic PMN07
Cos()
Angular distribution219 000 events
6914 g389 daysS/B = 40
NEMO-3
100Mo
E1 + E2 (MeV)
Energy sum spectrum219 000 events
6914 g389 daysS/B = 40
NEMO-3
100Mo
Background subtracted
• Data22 Monte Carlo
• Data22 Monte CarloBackground subtracted
« factory» → tool for precision test« factory» → tool for precision test
T1/2() = 7.11 0.02 (stat) 0.54 (syst) 1018 yrT1/2() = 7.11 0.02 (stat) 0.54 (syst) 1018 yr
12000
10000
8000
6000
4000
2000
0
Nu
mb
er o
f ev
ents
12000
10000
8000
6000
4000
2000
0
Nu
mb
er o
f ev
ents
/0.0
5 M
eV
NEMO 3:100Mo 2 results
Phys. Rev. Lett. 95 182302 (2005)
7.6 kg.yr 7.6 kg.yr
187Re Q = 2.47 keV
MIBETAMIBETA
m 2 = -141 211 stat 90 sys eV2
m15 eV (90% c.l.)
1 mm
Beta decay: MARE experiment
MicroBolometers of ArReO4
Full energy measurementNo systematic from sourceBut time response of sensor pile-up
MARE-I: 300 detectors FWHM ~20 eV ~100 – 500 s m2 –4 eV ( 5 years)
MARE – II : 5000 detectors (~2018) FWHM ~20 eV ~1 – 5 s m0.2 eV (10 years)
10 detectors
Today experiments have a mass of enriched source ~10 kg
To reject inverted hierarchy mass scenario, enriched source mass 1 ton
All projects have this goal but it is unrealistic to plane to go directly from 10 kg to 1 ton scale (understanding and control of the background)
Intermediate step at 100 kg scale is needed (as proposed by each project)
Talk focuses on the running experiments and on some 100 kg scaleprojects starting within 5 years
View of the field: present and future
F. Piquemal (CENBG) LP07 Daegu August 2007